Photographic developer composition



Jan. 24, 1967 A. 0. SMITH, JR 3,300,307

PHOTOGRAPHIC DEVELOPER COMPOSITION Filed Jan. 18, 1965 n --;/-SILVERHAL/DE EMULSION CONTAINING SOLUABLE I I J y; TANNING DEVELOPING AGENTSUPPORT 10' IN ALKALI SOLUTION SUPPORT UNTANNED EMULSION WASHED OFF\SUPPORT ALBERT 0. SMITH, JR.

INVENTOR.

United States Patent New Jersey Filed Jan. 18, 1963, Ser. No. 252,340 6Claims. (Cl. 9636) This invention relates to tanning photographicdeveloper-s and particularly to silver halide emulsions containingtanning developers.

Many photographic silver halide developers are recognized as tanningdevelopers including hydroquinone, catec-hol and the like. For instance,4-phenyl catechol has been incorporated in emulsions as disclosed inYackel, U.S. Patent 2,592,368 issued April 8, 1952. However, thisdeveloper must be dissolved in a coupler solvent and then used as adispersion in the photographic emulsion. For some purposes, the presenceof the coupler solvent tends to make the final coatings softer thandesirable Moreover, the preparation of the dispersion for addition tothe emulsion requires colloid which increases the total amount ofcolloid in the coated emulsion. This is undesirable Where the coatingsshould be thin and relatively hard. For these reasons, it has beendesirable to find a tanning developing agent which could be incorporatedinto photographic emulsions which would not require the use of a couplersolvent but would provide satisfactory hardening action, so thatwash-off relief images can be obtained following customary silver halidedeveloping.

Replacing 4-.pheny1 catechol with one of the more common, water solubledeveloper agents such as hydroq-uinone, catechol, or gallic acid has notresulted in obtaining a suitable wash-off relief image. Moreover, theoxidation products of these developers are colored and would producestain when incorporated in a relatively thin wash-oil relief typephotographic emulsion. Therefore, the requirements for a suitableincorporated developer have been stringent.

I have found a silver halide tanning developer combination which iswater soluble and can be added directly to the silver halide emulsion,but which has colorless oxidation products and is relatively free fromstaining.

One object of this invention is to provide a new tannin-g developer.emulsion which contains a tanning developer but which results in arelatively hard wash-off relief image and is free from staining. Afurther object is to provide a combination of gentisic acid with anauxiliary developing agent which can be used in a tanning developercontaining silver Additional objects will be halide photographicemulsion. apparent from the following disclosure.

The above objects are obtained by adding to a lightsensitive silverhalide emulsion a combination of gentisic acid and an auxiliarydeveloping agent. A useful concentration range 'for the gentisic acid isfrom about to 150 grams, with a preferred range of from about 25 to 75grams .per mole of silver. A useful concentration for the auxiliarydeveloping agent is from about 1 to 25 grams, with a preferred range offrom about 2.5 to 10 grams per mole of silver.

Various auxiliary developing agents are known in the art and may he usedwith gentisic acid, but the preferred auxiliary developing agent is asubstituted 3-pyrazolidone having the following general structureAnother object is to provide a photographic Y,

Patented Jan. 24, 1967 in which the R groups each represent varioussubstituents such as hydrogen, alkyl or aryl groups, for example, R canbe hydrogen or a group such as alkyl preferably containing from 1 to 4carbon atoms, or an aryl group of the benzene or naphthalene seriessubstituted or not, and R R R and R can be hydrogen atoms, or groupssuch as an alkyl group preferably of l to 4 carbon atoms or aryl such asphenyl.

The following compounds are representative of 3-pyrazo'lidone silverhalide auxiliary developing agents which are useful in the developercompositions of the invention:

l-phenyl-B-pyrazolidone l-p-tolyl-3-pyrazolidone5-phenyl-3-.pyrazolidone 5 -methyl-3-pyrazolidone1-p-chlorophenyl-3-pyrazolidone 1-phenyl-5-p'henyl-3-pyrazolidonel-m-tolyl-3-pyrazolidone 1-phenyl-5-rnethyl-3-pyrazolidone l-p-tolyl-5-phenyl-3-pyrazolidone 1 m-tolyl-3-pyrazolidone1-p-methoxyphenyl-3-pyrazolidone 1-acetamid'op'henyl-3 -.pyrazo.lidone1-phenyl-2-acetyl-4,4-dimethyl-3-pyrazolidone l-phenyl-4,4-dimethyl-3-pyrazolidonel-m-aminophenyl-4-methyl-4apropyl-3-pyrazolidonel-o-chlorophenyl-4-methyl-4-ethyl-3-pyrazolidone 17)l-m-acetamidophenyl-4,4-diethyl-3-pyrazolidone L8)1-p(fl-hy-droxyethylphenyl)-4,4-dimethyl-3- pyrazolidone l9l-p-hydroxyphenyl-4,4-d-imethyl-3-pyrazolidone (20)1-p-methoxyphenyl-4,4-diethyl-3-pyrazolidone (21 1-p-tolyl-4,4-dimethyl-3 -pyrazolidone (22) 1- 7-hydroxy-2-naphthyl)-4-methyl-4-n-propyl-3- pyrazolidone (23)1-p-diphenyl-4,4-dimethyl-3-pyrazolidone (24) l-p- ,B-hydroxyet-hylphenyl -3 =pyrazolidone (25) 1-o-tolyl-3-pyrazolidone (26)l-o-tolyl-4,4-dimethyl-3-pyrazolidone The following examples areintended to illustrate our invention but not to limit it in any way.

Example I An unhardened gelatin fine-grain silver chloride photographicemulsion which contained a coating aid and a pyrazo'lidone developingagent was split into two portions. Hydroquinone was added to Portion Aand \gentisic acid was added to Portion B. Both portions were coated ona paper base. Samples of these coatings werelgiven'a reflex exposure toa line copy and immersed in a 4% sodium carbonate activator for oneminute and then washed in F. water. It was :found that the samplecontaining gentisic acid produced sharper and more uniform images thandid the hydroquinone-containing sample. It was noticed thehydroquinone-containing coating was very susceptible to aerial oxidationwhen wet with the alkaline solution, and it exhibited decreased activityafter storage.

When samples of the above coatings were held for several weeks and thenexposed, activated, and washed it was observed that thege-ntisic-contai-ning coating gave results similar to that of the freshcoating; whereas, the hydroquinone-containing coating, due to thesolubility, vapor pressure, etc., of the hydroquinone, showed poordevelopability, undesirable stain, etc., which indicated that thehydroquinone did not remain in the emulsion layer during storage buttended to sublime out of the element and wander to other samples inclose contact with the element containing the incorporated hydroquinone.

Example 11 An unhardened gelatin silver chloride emulsion whichcontained a coating aid and a 3-pyrazolidone developing agent wasdivided into several portions. Gentisic acid was added to one portionwhile either gallic acid, pyrogallol or catechol were added to otherportions of the emulsion. The emulsion samples were then coated on asuitable support and dried. Samples of each of these coatings weretested as described in Example I above. The gentisic :acid coatingproduced processed samples of good uniformity which were free of stain;whereas, the samples containing either gallic acid, pyrogallol orcatechol, due to their instability and solubility under theseconditions, exhibited poor uniformity and/or disad vantageous stain.

Example III An unh-ardened gelatino silver halide photographic emulsion(predominantly silver chloride), containing one mole of silver halide,340 grams of gelatin and 5700 grams of water, was jelled, noodled, andwashed for onehalf hour with water then melted at 40 C. and thefollowing additions made:

This emulsion was coated on a film support and designated Coating A.

The following additions were made to one mole of a photographic emulsionof the type described above:

50 ml. of 15% aqueous saponin solution 660 ml. of gentisic acid (7.5%aqueous solution) 50 ml. of 1-phenyl-3-pyrazolidone (5% in methylalcohol) water to make a total of 4250 grams.

The treated emulsion was then coated on a film support and designatedCoating B.

When processed in an alkaline activator containing sodium carbonate at apH above 9, Coatings A and B exhibited the following sensitometriccharacteristics:

Relative Speed 7 max Coating A 4. 9 Coating B 5. 0

It will be noted that Coating B exhibited a higher gamma and D thanCoating A.

It was also observed that Coating A was softer and more subject tophysical damage during handling than Coating B due apparently to thepressure of the oily solvent in Coating A which was necessary todisperse the 4- phenyl catechol. The need for additional gelatin in the4-pheny1 catechol dispersion also renders it difficult to obtain thin,low gelatin-containing coatings.

Coatings containing 4-phenyl catechol tend also to be more allergenicthan coatings containing gentisic acid, and due to the need for the oilsolvent, are more difficult to coat without running into repellancy,etc.; in addition, the incorporated 4-phenyl catechol tanning developeragent has a tendency to autoharden during storage.

Example 1V Coatings A and B of Example 3 above were bathed in thealkaline activator, described above, in the dark for one minute. Thenthe top half of each coating was exposed, while in the activator, to aphotoflood lamp at about 12 inches for 4 minutes. The strips weresubsequently washed in F. water.

The exposed half of Coating B contained an image as evidenced by anoverall silver deposit, Whereas, the exposed half of Coating A did notcontain an image and was as clear as the unexposed bottom half. It wouldappear then, that the gentisic acid dilfuses from the emulsion lessreadily than does the 4-phenyl catechol and is, therefore, available fordevelopment after the initial bathing prior to the exposure.

Example V A coating was prepared as follows:

To 0.15 mole of a fine-grained 99 percent chloride orthochromaticallysensitized chloroiodide emulsion (AC-1381) was added:

Cubic centimeters 15.3 percent saponin 7.5 Semicarbazide, HCl (5 percentin distilled Water at pH 5.6:03) 12 Gentisic acid (7.5 percent indistilled water at pH 6.0) 100 4-methyl-1-phenyl-pyrazolidone-3 (5percent in CH OH) 7.5

Distilled water to 642 g.

The resulting melt contained about 4.3 percent gelatin. It was coated ona cellulose triacet-ate film support to give 690 mg. of gelatin persquare foot and 400 mg. of silver halide per square foot. The film wasexposed to an image and processed in an alkaline activator containing 3percent sodium carbonate. The non-image areas were then removed byWashing in warm water. This emulsion gave an excellent negative image.

Example Vl When either gentisic acid or 4-methyl-1-phenyl-3-pyrazolidone were used separately as in the emulsion of Example I, therewas either no image or a very faint image resulting from such use. Alonethey are not highly active developing agents at the pH of the activator.The oxidation products of each developing agent, gentisic acid or4-rnethyl-1-phenyl-3pyrazolidone, are colorless and remain so even whenused in combination. When 4-pheny1 catechol hydroquinone,p-phenylenediamine and pyrogallol or gallic acid are used in thissystem, the oxidation products are colored and produce stain.

Example VII Photographic emulsion as in Example I, containing thecombination of gentisic acid and 4-methyl-1-phenyl-3- pyrazolidone werecompared with 4-phenyl catechol incorporated in similar emulsions inalkaline activator solutions, i.e., 4 percent aqueous sodium carbonate.The developed fogged strips were washed in water at about 90 F. and theemulsion containing the 4-pheny1 catechol was completely washed away,whereas the gentisic acidpyrazolidone containing emulsion was hardenedenough to remain on the film support without any reticulation or edgesloughing.

I It will be appreciated that various film supports known in the art maybe used such as paper, cellulose ester, plastic supports such aspolyethylene, polyethylene terephthalate, etc. These supports may beoxidized, electron bombarded, etc., to improve adhesion. The silver halide emulsion may be of the usual negative type or may be a directpositive emulsion. A pigment may be added to the emulsion in order toincrease the density if so desired and the support over which theemulsion is coated may have previously been subbed, coated with variouscoating composition to improve the hydrophilic character of the supportor the like. In addition, the relief image may be subjected to varioustreatments known in the art to improve its receptivity to greasyprinting inks or the element itself may be subjected to treatments toimprove the relative difference in attraction to greasy printing inks toimprove the printability of the element for use as a printing plate.

In the accompanying drawings, I have shown a typical support at variousstages in my process. As shown in FIG. 1 a support is coated with agelatino-silver halide emulsion 11 containing a substantially watersoluble tanning developing agent. This material is exposed and developedby immersion in an alkaline solution to form images of silver andhardened gelatin as shown at 12 in FIG. 2. The remaining unhardenedgelatin and silver halide 13 in FIG. 2 is then washed off by treatmentof the support with Warm water to leave images 14 of hardened gelatin onthe support 10 as shown in FIG. 3.

The hydrophilic colloid is preferably gelatin, but may be any otherhydrophilic colloid known in the art which is tanned by gelatin tanningagents or may be a combination of gelatin and a similar hydrophiliccolloid which would provide a suitable tanning colloid layer.

Although this tanning developer combination is particularly useful inpreparing a lithographic printing plate, since a silver halide emulsionincorporating this developer combination provides a hard relief imageand can be coated in a relatively thin layer, it will be appreciatedthat this tanning developer combination may be used in otherphotographic applications where a tanning developer is desired to beincorporated in the emulsion. Typical emulsions where such a developerwould be used are described in Yackel, US. Pat. No. 2,592,368, issuedApril 8, 1952, and Yutzy et al., U.S. Pat. No. 2,716,059, issued August23, 1955, and the like.

Here and in the appended claims wherein it is stated that the emulsionvehicle is substantially unhardened this is defined as a meaning notharder than would be the case with gelatin containing 0.25 ounce offormaldehyde (40 percent solution diluted 1 to 3 with water) per pound,when freshly coated, or 0.1 ounce of the solution per pound for a sampleaged three to six months. Emulsion layers appreciably harder are notvery satisfactory for use in my process or that of the above copendingapplication.

In general, when utilizing the usual type of photographic gelatin,useful results are obtained without addition of hardener to theemulsion. In case the gelatin in use has poor physical properties then asmall amount of hardener such as formaldehyde may be used.

The emulsion layer may be exposed in the usual manner under a linedrawing and is developed by immersion in an aqueous solution of analkali such as sodium or potassium carbonate, an alkali metal hydroxidesuch as sodium hydroxide, potassium hydroxide, or ammonium hydroxide, oran amine. The addition to the alkaline solution, of other materials, isalso helpful in obtaining a satisfactory relief image. For example, theaddition of sodium hydroxide to a sodium carbonate solution improves thesensitometric characteristics of the material as well as the reliefproperties. The addition of reducing agents such as ascorbic acid,hydrazine hydrochloride, sodium sulfite, in small quantities, sodiumbicarbonate and urea, are also advantageous.

After development of the exposed material in the alkaline solution, theelement is washed with warm water to remove the unexposed andundeveloped colloid and silver halide and then dried. By warm water Imeans water at a temperature above F. to F. or higher.

It will be appreciated that the light-sensitive emulsions are preparedunder normal darkroom or safelight conditions as required.

The emulsions of this invention are useful in the colloid transferprocess as described in US. Patents 2,596,- 756 and 2,725,298. sionresults in hardening the exposed area of the image which then adheres tothe support. The unexposed and, therefore, unhardened area istransferred to a suitable absorbent surface such as a paper receivingsheet when the emulsion is contacted against the paper receiving sheet.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

I claim:

1. A process for providing a relief image comprising developing anexposed silver halide emulsion comprising a substantially unhardenedgelatin vehicle and dispersed in said vehicle silver halide and atanning developing agent comprising gentisic acid and a 3-pyrazolidonesilver halide developing agent by imbibing into the gelatin vehicle anaqueous alkaline solution and removing the undeveloped silver halidecontaining vehicle.

2. A process of claim 1 in which the pyrazolidone is 1-phenyl-3-pyrazolidone.

3. A process of claim 1 in which the pyrazolidone is4-methyl-1-phenyl-3-pyrazolidone.

4. A process of claim 1 in which the pyrazolidone is2-acetyl-4-methyl-1-phenyl-3-pyrazolidone.

5. A process of claim 1 in which the undeveloped silver halide isremoved by washing with warm water.

6. A process of claim 1 in which the undeveloped silver halidecontaining vehicle is transferred to an absorbent surface.

References Cited by the Examiner UNITED STATES PATENTS 2,716,059 8/1955Yutzy et al 9695 2,751,297 6/1956 Hood et al. 96109 3,192,046 6/1965Kennard et al. 9695 OTHER REFERENCES Henn et al.: Phot. Sci. and Tech.(II) 1954, pp. 126- 130.

Mees: Theory of the Photographic Process 1954, Mac- Millian Company, NewYork, pp. 560 and 580582.

NORMAN G. TORCHIN, Primary Examiner.

A. D. RICCI, Assistant Examiner.

Development of the exposed emulv

1. A PROCESS FOR PROVIDING A RELIEF IMAGE COMPRISING DEVELOPING ANEXPOSED SILVER HALIDE EMULSION COMPRISING A SUBSTANTIALLY UNHARDENEDGELATIN VEHICLE AND DISPERSED IN SAID VEHICLE SILVER HALIDE AND ATANNING DEVELOPING AGENT COMPRISING GENTISIC ACID AND A 3-PYRAZOLIDONESILVER HALIDE DEVELOPING AGENT BY IMBIBING INTO THE GELATIN VEHICLE ANAQUEOUS ALKALINE SOLUTION AND REMOVING THE UNDEVELOPED SILVER HALIDECONTAINING VEHICLE.